Vanadium tunning amorphous iron phosphate encapsulated iron phosphide on phosphorous-doped graphene promoted oxygen reactions for flexible zinc air batteries

The zinc air batteries (ZABs) are emerging as potential energy storage devices, because of its low-cost, safety, and high energy density. The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) mainly occur at the air-cathode, which play the key role in the ZAB's performance. However, the sluggish oxygen reactions require an overpotential and multiple electron transfer steps. Herein, the unique crystalline/amorphous nanostructure of V-doped Fe2P/FePOx @PG hybrid has been prepared, which showed the electronic structure tuning and synergistic effect. The catalyst exhibited a small overpotential of 270 mV at 10 mA cm−2 for OER, and a high half-wave potential of 0.84 V for ORR. When serving as air-cathode for ZABs, it showed ultralong durability of 600 h with high peak power density of 137 mW cm−2. The solid-state ZABs demonstrated superior performance with different testing conditions, offering high potential to apply to the next generation flexible energy storage devices.